1. Field of the Invention
The present invention relates to a sheet processing apparatus which produces a sheet bundle of a folded booklet shape and an image forming apparatus which includes the sheet processing apparatus.
2. Description of the Related Art
In related art, there has been an image forming apparatus for forming an image on a sheet with a sheet processing apparatus which produces a booklet by binding and folding the bundled sheets on which images are formed by the apparatus main body, as disclosed in US20070060459, for example.
With such an image processing apparatus of the related art, the sheets conveyed to a stack tray are aligned after being received sequentially at a binding position where the center parts of the sheets are to be bound. Then, the sheet bundle is conveyed to a folding position which is located downstream the binding position to match the center part with a fold-line to be folded after or without being bound at the center parts of the sheets. Then, the sheet bundle is thrust at the center part by a thrusting member so as to be thrust into a nip of a pair of folding rollers. Accordingly, the sheet bundle is folded while being conveyed by the pair of folding rollers.
The top part of the folded portion is processes so that the fold-line is reinforced by a pair of press rollers which is different from the pair of folding rollers being moved along the fold-line of the sheet (in the direction orthogonal to the sheet conveying direction). Then, the sheet bundle subjected to the folding process is conveyed and discharged to a folded bundle discharging tray. In this manner, a booklet can be obtained as a product.
In the sheet processing apparatus in the related art, as described above, the stacked sheets or the stacked sheet bundle have been conveyed to the folding position at the downstream side of the conveying direction after being aligned at the binding position even when performing the folding process without the binding process (hereinafter, called non-binding folding). Therefore, there is a possibility that folding accuracy is declined by shifting of the sheets during the sheet bundle is conveyed. Further, since the sheet bundle conveyance takes time, productivity is decreased.
The present invention provides a sheet processing apparatus which has high folding accuracy and high productivity while suppressing poor conveyance stacking.